As long as you don't have a shitty fan, or an overloaded CPU, you should be fine.
My laptop stays on for days and days and days at a time, and only gets shut down for Windows Updates, when a program prompts me to for installation/uinstallation, or if some programs start acting weird and I use restarting as a troubleshooting step. I usually run iDung, or 1-2 VMs running RiD bots. I usually stick around ~20-40% CPU, and my vents on my laptop are huge.
Normal load CPU + good fan + good airflow = fine for running overnight.
Also, random note, I've left my iMac on, without restarting, for weeks before. It's fine as long as your cooling system isn't shit and your CPU isn't maxed out.